Ron Passerini created OLINGO-1625:
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Summary: The serializers have performance issues when Entities
contain very large numbers of Properties
Key: OLINGO-1625
URL: https://issues.apache.org/jira/browse/OLINGO-1625
Project: Olingo
Issue Type: Bug
Components: odata4-server
Affects Versions: Version (Java) V4 5.0.0
Reporter: Ron Passerini
Fix For: (Java) V4 5.0.1
I've implemented an OData service that serves up some large datasets in a
streaming fashion. Some of those datasets have large numbers of fields (over
1,000). When I requested one of them which was around 350M in size, it took way
longer than expected.
I profiled the request in IntelliJ's profiler and found that over 75% of the
CPU cycles were spent in String.equals() comparing column names in the
serializers. This is because there is an O(N^2) issue that for every column
selected (in my case all of them) it will iterate across the entire list of
entity properties looking for the one with the same name.
I have already implemented a fix whereby before doing the property
serialization, the serializer builds a hash map of property-name-to-property,
making the resulting algorithm O(N) with the number of properties being
serialized.
After profiling the change, again in IntelliJ's profiler, the String.equals()
which was over 75% before, is now under 1%.
I will be creating a patch and attaching it momentarily.
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